1. Department of Radiation Oncology, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
2. Department of Pathology and Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
3. Department of Microbiology and Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea